The overarching goals of this research are to evaluate follow-up status, 1 to 2 years after baseline, of a cohort of persons aged 75-85 at baseline who were found to have functional limitations (EPESE performance battery score of 4-9) but who were able to walk 400 meters in a test done in the Hebrew Home rehabilitation unit. Specific questions to be addressed include: 1.What is the incidence of inability to walk 400 meters in at-risk older persons who were found to be able to walk this far at baseline? 2.What are the main chronic diseases, impairments, and demographic characteristics which predict incident mobility loss? 3.What questions can be asked to impute who will be unable to walk 400 meters in an objective test of walking this distance in the clinic. This methodologic work is currently being used in a multisite trial of exercise to prevent mobility loss, defined using the test developed for this project.